On 3/5/25 7:39 AM, Robin Dapp wrote:
Hi, when merging two vsetvls that both only demand "SEW >= ..." we use their maximum SEW and keep the LMUL. That may lead to invalid vector configurations like e64, mf4. As we make sure that the SEW requirements overlap we can use the SEW and LMUL of the configuration with the larger SEW. Ma Jin already touched this merge rule some weeks ago and fixed the ratio calculation (r15-6873). Calculating the ratio from an invalid SEW/LMUL combination lead to an overflow in the ratio variable, though. I'd argue the proper fix is to update SEW and LMUL, keeping the ratio as before. This "breaks" bug-10.c but its check only checked for a workaround anyway so I turned it into a run test. For V2, Ma Jin helped minify the PR's test and provided a larger test case for bug-10. Regtested on rv64gcv_zvl512b. Regards Robin PR target/117955 gcc/ChangeLog: * config/riscv/riscv-vsetvl.cc: Use LMUL/ratio from vsetvl with larger SEW. gcc/testsuite/ChangeLog: * gcc.target/riscv/rvv/base/bug-10.c: Convert to run test. * gcc.target/riscv/rvv/base/bug-10-2.c: New test. * gcc.target/riscv/rvv/base/pr117955.c: New test.
OK jeff
